Callaway alleges that Acushnet's latest version of the popular Titleist Pro V1 and Pro V1x balls infringe on patents Callaway acquired as part of its purchase of competitor Top Flite in 2003.

Acushnet, a division of Fortune Brands based in Fairhaven, Mass., filed a separate lawsuit against Callaway. It alleges Callaway's Tour i and Tour ix premium golf balls infringe on nine Acushnet patents. The patents involve things such as dimple pattern, core construction and the manufacturing process.

The dueling lawsuits in Delaware federal court are part of a lingering battle between the two golf companies, which are fierce rivals in the ball business.

Titleist's Pro V1 and Pro V1x are the market leaders in premium golf balls. The Pro V1 family had a total market share of 25.1 percent for the month of January, according to Golf Datatech, an industry research firm.

A Callaway spokeswoman said that while the Tour i series trails in market share, Callaway has a wide lineup of golf balls and has gained market share over the past year.

Both companies said the lawsuits will not prevent retailers from selling the Pro V1 family or the Tour i series – at least for now. Patent cases often take months or years to work their way through the courts.

This is the second round of courtroom salvos for the two companies. In late 2007, Callaway won a long-running patent infringement case against Acushnet that said the Pro V1 infringed on four Callaway patents.

The jury verdict led Acushnet to implement an exchange program with retailers in December. Retailers could trade older models of the Pro V1 with the new 2009 Pro V1 models. Acushnet said it designed the new Pro V1 balls so they don't infringe on Callaway's patents.

Callaway disputes that claim. “We are disappointed to discover that Titleist and Acushnet have again used Callaway technology in their Pro V1 golf balls,” said Steve McCracken, Callaway's chief administrative officer.

Joe Nauman, Acushnet's executive vice president and legal counsel, said Callaway's latest lawsuit alleges infringement of two patents that were not part of the prior case. Acushnet says the lawsuit is without merit.

Acushnet also continues to fight the prior case. It appealed several decisions by the judge, among other matters, to a higher court, Nauman said.

Moreover, after the jury verdict in Callaway's favor, Acushnet received a ruling from the U.S. Patent & Trademark Office declaring that the four patents in the prior case were invalid.

Callaway is appealing the Patent & Trademark Office ruling on one of the patents, Nauman said, and is expected to challenge them all.

“It's regrettable that one of our competitors would rather compete in the courtroom than in the pro shop,” Nauman said. “While all litigation is uncertain, we remain confident we will prevail.”